iTunes During Sync - This Computer is not authorized

Hello there, WAR3Z-CH3WY.

It sounds like you are being repeatedly prompted to Authorize your computer, even though it is already authorized. This can occur for a number of reasons. The why and how to resolve them is also outlined in the following Knowledge Base article:

If iTunes repeatedly prompts you to authorize your computer - Apple Support

Although all of these are steps to look through, the most common seems to be the following:

Authorize your purchases with the correct account name

The items you're trying to play might have been purchased using a different iTunes Store account. To determine which account was used to purchase an item, follow the steps below:

1. Select a purchased song in your library.
2. Mac: From the menu bar at the top of your computer screen, choose File > Get Info.
   Windows: Press Control and B on your keyboard to turn on the iTunes menu bar. From the menu bar, choose File > Get Info. Learn more about menus in iTunes for Windows.
3. Click the File tab. Make note of the Account Name that appears in the list. This is the account name (Apple ID) that you need to use when you authorize your computer to play this purchase.
   The Apple ID that appears is the one that you used when you purchased the item. The Apple ID you used to purchase the item doesn't change, even if you change your Apple ID.
4. Authorize your computer.

If you authorized the Apple ID that is shown in the Summary File tab, check your purchase history for that Apple ID. If your purchase history doesn't reflect the purchase of the items in your iTunes library, think about any other Apple ID you might have created, and authorize your computer for that Apple ID.

If you forgot the password to one of your accounts, recover it using Apple's password-recovery website.

Thanks for reaching out to Apple Support Communities.

Kind Regards.

Hello again.

Thanks for the follow up on your issue. Due to the nature of your question, it may be best if we get you in contact with someone who can look into this further. You may find more information by using another one of Apple's support resources - https://getsupport.apple.com.

Cheers.